Process for preparing alkaline earth cyanamides



RTH CYANAMIDES Feb. 26, 1935. N. czmao ET AL PROCESS FOR PREPARING ALKALINE EA Filed Feb. 7, 1930 Flow Sheer Producer 9 .5

Mixed gas 11 N H GO Remainder C0 Compressing rev 27 arm.-- CO Mixed gasDI N H Remainder CO Compress ing to 200 atm. m comm 6 Washing wikl copper solution Mixed gas IY Nitrogen N,

Synthesis gas or Convert gas 75 Vol H, 25 Vol /0 N Ammonia synfhesis 2N +5H 2NH and waste gas: MH -56; H N flo Condensation-NH, and C02 Residue gas Inven for [MW ml l'ion CO Patented Feb. 26, 1935 PROCESS FOR PREPARING ALKALINE EARTH CYANAMIDES Nikodem Caro, Berlin-Dahlem, Albert Rudolph Frank, Berlin-Halensec, and Hans Heinrich Franck, Berlin-Charlottenburg, Germany ApplicationFebruary 7, 1930, Serial No. 426,784 In Germany February ,8, 1929 FFICE ther converting the carbon monoxide-hydrogen moma consists in preparing the initial gas mlxwaste gas from the cyanamide furnace: ture for the ammonia synthesis fiom coke and 3. In the hydrogen contact furnace. steam or from coke and air pressure copper separator.

The combined contact conversion.

'1 e fixation of the 25 way to fertilizable calcium cyanamide by passing cyana-mide formation takes place, contains, for

example 51% of carbon monoxide, 7% of nitrogen, 6.2% of carbon dioxide and, after condensation of the ammonia and the carbon dioxide, 65% of carbon of hydrogen and 17% of nitrogen.

t has now been found according to this inventhe carbon monoxide:

1. Carbon monoxide from producer gas. 2. Carbon monoxide from the pressure copper There are also two possible methods for fur nitrogen necessary for the 4. Removal of the hydrogen by means of the washing process or the Linde carried out as follows (according to 1 and 3):

in a Linde separator, the

united wit h the synthetic nitrogen and hydrogen, so much nitrogen is added washing process or from the Linde separator. that the, composition of 75% hydrogen and 25% synthetic gas is attion of cyanamide.

- proportions of gas contains cium cyanamide a quantity of ing to 2.5 cubic metres.

'ticularly pure, as

tained and synthesized in the ammonia synthesis to, form ammonia which is conducted with the above mentioned carbon monoxide over the calcium carbonate. Here calcium cyanamide and a waste gas composed of ammonia, carbon dioxide, carbon monoxide, hydrogen and nitrogen are formed. After separating the ammonia and carbon dioxide the remaining gas composed of nitrogen, hydrogen and carbon monoxide is added either to the mixed gas 1 serving for the ammonia synthesis before this gas passes into the hydrogen contact furnace or 3 passing out of the hydrogen contact furnace according to the content of carbon monoxide.

The waste gases from the cyanamide reaction, after the ammonia and carbonic acid have been removed, are compressed to the pressure of the hydrogen contact furnace, the pressure copper washing apparatus or the Linde separator according to which stage of the ammonia synthesis they are introduced.

The quantitative proportions are shown in the following example.

In :the preparation of calcium cyanamide from ammonia and carbon monoxide the quantity of carbon monoxide passed through amounts, depending on the percentage proportion of CO:l lI-I3 employed, to about 540 cubic metres per kg. of

N(CaCI l2). Of 'thisquantity employed there is, however, used up during the CO2 or H2 formation respectively the quantity, fairly constant for all COtNHs, of 2-2.5 cubic metres per kg. of N CaCNz If, therefore, the CO is passed into the cyanamide formation stage, the waste for every kilogram of N in the calhydrogen amount- If the gas freed from the nitrogencompounds is now allowed to pass into the pressure copper washing apparatus under 10 to 20 atmospheres these 2.5 cubicmetres of hydrogen are directly available in a pure form for the ammonia synthesis and here also result in exactly 1 kg. .of' nitrogen, this time in the form of NH3. The CO returns into the cyanamide process. and must" be replaced in full by the addition of 2.5 cubic metres of fresh gas. The synthesized NHs itself also serves for the formation of cyanamide. V

The combination according to this invention offers the following advantages:

The carbon monoxide in the formation of calcium cyanamide from ammonia and calcium carbonate serves only as an equilibrium displacer by removing the water of reaction; it is converted thereby to carbon dioxide and hydrogen. An increasing amount of carbon monoxide'in the ammonia results in an increasing percentage forma- The resulting gas, which contains 20-30% of the hydrogen originated according. to the water gas equation from the carbon monoxide which has been introduced, is parthe calcium carbonate acts automatically as a purifier. It is, therefore, particularly suitable for the ammonia synthesis cycle. A definite stage of operation, which occurs in both processes is, therefore, entirely or partially combined into one process according to this invention.

' We claim:-

1. Process for the production of calcium cyanamide from calcium carbonate, carbon monoxide and synthetic ammonia, consisting in separating carbon monoxide from an initial gas for the ammonia synthesis containing nitrogen, hydrogen and carbon monoxide, in synthesizing the hydrogen and nitrogen to ammonia, in causing to the mixed gas carbon monoxide thesis and the separated carbon monoxide for the 7 production of cyanamide.

2. Process for the production of calcium cyanamide from calcium carbonate, carbon monoxide and synthetic carbon monoxide from an initial gas for the ammonia synthesis containing nitrogen, hydrogen and carbon monoxide to react with steam in a hydrogen contact furnace, in separating the resultant carbon dioxide and monoxide, in synthesizing'the remaining gas containing nitrogen and hydrogen to form ammonia, in causing the ammonia with admixture of carbon monoxide to react with calcium carbonate, in separating the ammonia and carbon dioxide from the resultant gas, in feeding'the remaining gas to the initial gas containing carbon monoxide, hydrogen and nitrogen before passing through the hydrogen contact furnace, in separating the converted carbon monoxide from the gases leaving this furnace and causing the same together with ammonia to react with calcium carbonate.

3. Process for the production of calcium cyan amide from calcium carbonate, carbon monoxide and synthetic ammonia, consisting in causing the carbon monoxide from an initial gas for the ammonia synthesis containing nitrogen, hydrogen and carbon monoxide to react with steam in a hydrogen contact furnace, in separating the resultant carbon dioxide and monoxide, in synthesizing to ammonia the resultant gas containing nitrogen and hydrogen, in causing the ammonia with an admixture of carbon monoxide to react with calcium carbonate, in separating the ammonia and carbon dioxide from the resultant gas, in compressing the remaining gas and feeding same to the ammonia synthesis gas posterior the hydrogen contact furnace, and in separating the unconverted carbon a hydrogen contact furnace in reactive contact with steam and initial gas for the ammonia synthesis containing carbon monoxide and nitrogen, separating the carbon dioxide from the gases issuing from, the furnace, compressing these gases to the pressure of a pressure copper washing apparatus and passing them through this pressure copper washing apparatus to there separate these gases into hydrogen and unconverted carbon monoxide, and in employing the separated hydrogen for the ammonia synthesis and the separated for the production of cyanamide. V

5. A process for the production of calcium cyanamide from calcium carbonate, carbon monoxide and synthetic ammonia, comprising the stages of passing synthetic ammonia and carbon monoxide into reactive contact with calcium carbonate, removing ammonia and carbon dioxide from the resulting gases, conducting the remaining gas into a hydrogen contact furnace in rearnmonia, consisting in causing the monoxide from the gases 1 leaving this furnace and causing the same togethproduction of cyanamide.

6. A process for from calcium carbonate, calcium monoxide and dioxide from the contact furnace,

NIKODEM CARO. ALBERT R. FRANK HANS HEINRICH FRANCK. 

